Steel fastening pin for a draw die bead



Oct. 21, 1969 w. R. HERMAN ETAL 3,473,363

STEEL swims PIN FOR A mmw DIE BEAD Filed March 17, 1957 FIG. .2

R HERA/IA N KOR TESOJA INVENTORS A7 TORNEVS United States Patent3,473,363 STEEL FASTENING PIN FOR A DRAW DIE BEAD William R. Herman,Allen Park, and Victor A. Kortesoja, Livonia, Mich., assignors to FordMotor Company,

Dearborn, Mich., a corporation of Delaware Filed Mar. 17, 1967, Ser. No.623,870

Int. Cl. D21d 22/00; F16d /06 US. Cl. 72347 2 Claims ABSTRACT OF THEDISCLOSURE This invention is concerned with a particular construction ofrivet employed in securing draw die beads to the surface of draw diesand to the combination of the draw die, the draw die bead and the drawdie bead steel fastening pin.

BACKGROUND OF THE INVENTION Draw dies are widely used in the fabricationof sheet metal parts which must be produced in large volume. These drawdies are routinely provided with draw die beads which are so located asto secure the sheet metal being drawn firmly between the cooperatingdies while the draw is being made so that the metal cannot flow exceptin the direction for which the dies have been designed and constructed.The use of such draw die beads is conventional and shall not further bedescribed.

The means used to secure the draw die beads to the draw dies have in thepast been far from satisfactory. Such fastening means must be cheap,reliable and totally resistant to the high mechanical stresses incidentto operation and to the thermal stresses sometimes encountered in thelocal heat treatment of the dies. This invention is addressed to theprovision of such a fastening means and the cooperating draw die anddraw die head.

3,473,363 Patented Oct. 21, 1969 DESCRIPTION OF THE INVENTION Thisinvention is best understood in conjunction with the drawings in which:

FIGURE 1 is a view of the draw die bead steel fastening pin upon whichthis invention is predicated; and

FIGURE 2 is an enlarged section of a portion of the serrations shown ingross in FIGURE 1; and

FIGURE 3 is a cross section taken through the serrated portion of thedraw bead steel fastening pin showing the air escape groove; and

FIGURE 4 is a cross section of a portion of the draw die, the draw diebead and the draw die bead rivet taken normal to the axis of the drawdie bead.

The draw die bead steel fastening pin depicted in FIG- URE 1 has beenfabricated from SAE 1045 steel to take advantage of the economy andready hardenability of this steel. One end of this rivet is serrated asshown in FIG- URE 1 in gross and in detail in FIGURE 2. This serratedportion is 0.75 inch (1.91 cm.) long. The diameter of the teeth of theserrations is from 0.200 to 0.198 inch (0.508 to 0.503 cm.) and thediameter of the base of the serrations is from 0.180 to 0.177 inch(0.456 to 0.450 cm.). A cylindrical section 0.125 inch (0.317 cm.) longseparates the serrated portion from the tapered end portion. It ispreferred that elements of the truncated cone represented by thistapered portion include an angle of about four degrees although undersome circumstances this taper may be replaced by a straight cylinder.

This draw die steel fastening pin is received in coaxial holes in thedraw die and the draw die bead. The diameter of the hole in the draw dieshould be about 0.191 inch (0.485 cm.). The diameter of the coaxial holein the draw die bead should be large enough to permit passagetherethrough of the serrated portion of the draw die steel fastening pinand to interfere with the tapered portion. A suitable diameter has beenfound to be 0.203 inch (0.516 cm.). The draw die bead steel fasteningpin is hardened in the portion in contact with the draw die and lesshard in the portion in contact with the draw die head.

The following tabulation is presented to demonstrate the resultsobtained with this type of fastening between a draw die and the draw diebead.

1 Present standard draw bead steel 1,730 pounds.

fastening pin in .1865" diameter holes.

2 Present standard draw bead steel 1,760 pounds.

fastening pin in .1865 diameter holes, epoxy glued.

3 .200" Q.D. knurled draw bead steel 1,035 pounds.

fastening pin in .191 diameter holes.

4 .200 OD. knurled draw bead steel 2,450 pounds.

fasteciliing pin in .191 holes, epoxy g ue 5 .200 O. D. draw bead steelfastening 4,610 pounds broke bead, one draw pin with circular teeth in.191 dibead steel fastening pin, pulled up. ameter holes.

6 .200" O. D. draw bead steel fastening 3,650 pounds broke one draw beadsteel pin with circular teeth in .191 (11- fastening pin and bead.ameter holes.

7 .200 0.1). draw bead steel fastening 1,500 pounds draw bead steelfastening p n with circular teeth in .193.195 pins pulled out of hole.diameter holes.

8 .200" OD. draw bead steel fastening 1,340 pounds draw bead steelfastening pin with circular teeth in .196 dipins pulled out of hole.ameter holes.

9 .200 OD. draw bead steel fastening 1,750 pounds draw bead steelfastening pin with circular teeth, tapered pins pulled out of holes.

head so no peening needed in .195- .196" diameter holes.

We claim as our invention:

1. A draw die and a draw die bead securely fastened together, said drawdie bead and said draw die having coaxial openings for the reception ofa draw die bead steel fastening pin and a draw die bead steel fasteningpin occupying such openings, said draw die bead steel fastening pinbeing hardened in the portion in contact with the draw die and beingless hard in the portion in contact with the draw die bead, saidhardened portion of the draw die bead steel fastening pin being serratedand in which 10 2,967,448

the serrations are constructed to favor penetration of the draw die beadsteel fastening pin into the draw die and to oppose the withdrawal ofthe draw die bead steel fastening pin, the upper end of the draw diebead steel fasten- 4 2. The structure recited in claim 1 in which theportion of the draw die bead steel fastening pin in engagement with thedraw die bead is tapered with the lesser end or the taper adjacent thedraw die.

References Cited UNITED STATES PATENTS 1,978,329 10/1934 Rosenberg 85-212,028,528 1/1936 Sipe 852l 1/1961 Hallock 85-21 MILTON S. MEHR, PrimaryExaminer U.S. Cl. X.R.

ing pin being no higher than flush with the draw die bead. 15 72- 350;8521

